When you remove it, you will see an O ring. If it swells on you, don’t stress. This one did. It would not fit back into its groove. I put it on a piece of foil and put it in a freezer. That made the rubber go back to its memory. It fit perfectly after and retained that size after returning to room temperature. Here it is installed.
Now to install it. The motors shaft is eccentric so it acts like a camshaft on to pump valve pins.
If you notice the hole in the end of the shaft, it is off set. Also note the “F” embossed on the white plastic.
I rotated the pump shaft under that silver encased needle bearing on the shaft so the hole in shaft on its narrowest point in the shaft to align with that “ F”. In this photo, I had not yet aligned it. I did that after painting and reinstalling iring
They are spring loaded, pushing inward. They ride on the bearing on that shaft so you cannot just reinstall the motor. I did that alignment and went in at a little bit of an angle. It get in enough to get against on of the pump pins to push it away. Once it pushed, allowed the motor to go into place.